The present invention relates to a regulated flow restrictor device. The invention is particularly useful for drip irrigation emitters, and is therefore described below with respect to this application.
Drip irrigation systems have come into widespread use for irrigating plants since they supply a minimum of water directly to the root region of the plants. Regulated emitters have also come into widespread use since they produce a fairly uniform output despite variations in the inlet pressure, and thereby enable drip irrigation lines to be of relatively long lengths and to be used over uneven terrain.
Many techniques have been developed for regulating emitters. Some involve varying the cross-section of a labyrinth in response to changes in the inlet pressure; whereas others involve varying the cross-section of a control chamber or of an outlet port in response to changes in the inlet pressure. Another proposed technique, as described in Eckstein U.S. Pat. No. 5,111,996, varies the effective length of a labyrinth in response to changes in the outlet pressure.